Born too early to experience hypersonic air travel, born too late to experience the golden age of the jet age. Born just on time to experience flying buses.

And what happens if there is a depressurization at height? Everybody would need a pressure suit !

Concorde's aircon was designed to be able to sustain an acceptable cabin pressure with, I think, two windows blown out. Acceptable as in O2 masks were usable until a safe altitude was eventually reached.

Would have been one hell of a draught blowing through the cabin!

I strongly suspect that anyone building a new high altitude super sonic airliner today would learn an awful lot about what they'd have to do by reading the Concorde thread in Tech Log.

The thing I find so surprising with such programmes is that they always want to take such a massive leap from Concorde. Yes it was developed during the 1970's but let's remember that the USA never got anywhere near to producing even an equivalent to it.
The leap in technology required to go from M2.0 to M5 is probably beyond that currently available and even if it is available would be so incredibly expensive as to preclude being commercial.
Technology demonstrators would need to be designed developed and tested well before such an aircraft could be produced.
Don't hold your breath....

That Concorde thread in Tech Log has been remixed for your reading pleasure of you google "concorde paulross" It even has a section on depressurisation!

That's interesting to know. Was this ever practically tested? Or was it all done with computer (or slide rule calcs) at the time?

Concorde was a wonderful aircraft which I viewed many times at LHR and CDG but never had the good fortune to ride myself. One of my few regrets in life but if I can go supersonic in another pax jet I would be interested.

I suspect any new hypersonic (or even supersonic) Part 25 aircraft would have to be certified based on the probability of sudden cabin depressurization being extremely remote (10-9/hr. in cert speak) - any other solution would be unworkable (passengers in pressure suits...). The Concorde couldn't be certified under todays rules using the small window solution.
That might well mean no windows aside from the flight deck, multiple redundancies in the pressurization systems, and greater margins on the structural side of the pressure vessel. Even then, there is a regulation regarding having to withstand a certain size fuselage hole (i.e.. bomb blast) that would need some sort of Equivalent Safety Finding (ESF).

Right, double-hull is mandatory. Add an inner hull, maybe from Fabric like Kevlar just for onetime fail-safe use. The outflow valves serial to monitor both hulls are able to pressurize.

Good point about Concorde, a new version would be the next sensible step. And does anyone remember HOTOL? A viable design binned by Thatcher because she wouldn't offer any support; a brilliant design but the funding needed to put it into practice was just too great for a private enterprise.

FARs call for holding cabin altitude below 40K feet at all times and not allowing it to go above 25K feet for more than 2 minutes. The "never exceed 40K" bit is not too hard for subsonic transports as that is about their cruise ceiling. The depressurized emergency decent challenge has always been the "not above 25K for more than two minutes" bit. Some of the more recent slippery designs have a real challenge generating enough drag to get down quickly enough to meet this. Starting at a higher altitude would bring the "never above 40K" into play and make the time to get below 25K even more of a challenge.

An interesting twist is considering use of a scoop to channel air into the passenger cabin in the event of a depressurization. If the scoop has a large enough cross section it should be able to pull enough air into the cabin to counter any hole up to the size that must be considered for certification. An interesting / troubling consequence, however, is that the process of compressing outside air via such a scoop could end up heating the air to an unacceptable temperature. You are left with two unpleasant choices, have cabin pressure drop well below that for 40K feet, or cook the cabin in the process of repressurizing via a large scoop.